The Heart, Coronary Circulation, Conducting System

Question 1

What is the only branch of the Ascending aorta?

Answer 1

The Coronary arteries

Question 2

What are the origins of the left and right Coronary arteries?

Answer 2

They originate from the left and right cusps of the aortic valve, respectively

Question 3

Wat is the anatomical position of the main stem of the left Coronary artery?

Answer 3

Main stem lies between the left auricle and the pulmonary trunk where it then enters the coronary sulcus

Question 4

What are the branches of the left Coronary artery?

Answer 4

• Circumflex branch
• left marginal branch
• anterior inter ventricular branch ( left anterior descending branch)

Question 5

What do the branches of the left Coronary artery supply?

Answer 5

• walls of the left atrium and left ventricle

- most of the inter ventricular septum and anterior part of the atrioventricular (AV) bundle

Question 6

Where does the right Coronary artery main stem emerge from?

Answer 6

passes between the right auricle and the pulmonary trunk

Question 7

What are the 3 branches of the right coronary artery?

Answer 7

• sino-atrial nodal branch
• right marginal branch
• posterior inter ventricular branch

Question 8

what is supplied by the right Coronary artery?

Answer 8

• walls of the Right atrium and ventricle
• sinu-atrial node and the atrioventricular node
• posterior part of the inter ventricular septum
• small areas of the walls of the left atrium and left ventricle

Question 9

where does the RCA anastomose with LCA?

Answer 9

anastomoses with the LCA in the coronary sulcus and the apex of the heart

Question 10

where does the LCA anastomose with the RCA?

Answer 10

anastomoses in the coronary sulcus and posteriorly at the apex

Question 11

What is the importance of the anastomoses between the coronary arteries?

Answer 11

The coronary arteries create a parallel circuit around the heart so if there is an occlusion then blood flow is not limited to a certain area of the heart

Question 12

What does the anastomoses between the coronary arteries allow to happen?

Answer 12

In times occlusion it allows the operation of a Coronary Artery Bypass Grafting to take place. Uses the great saphenous vein to form the vessels from the ascending aorta hence bypassing the occlusion.

Question 13

Which vessel does most of venous blood drain to in the heart?

Answer 13

the coronary sinus

Question 14

What is the anatomical position of the coronary sinus?

Answer 14

lies between L atrium and L ventricle and drains into the Right Atrium

Question 15

What are the 3 main veins of the heart? Which arteries are they associated with?

Answer 15

• great cardiac vein with the LAD
• middle cardiac vein with the Posterior inter ventricular
• small Cardiac vein with right marginal vein

Question 16

What are the components of the coronary conducting system of the heart?

Answer 16

• SA node
• AV node
• Atrioventricular bundle of His
• Right and Left bundle branches
• Purkinje fibres

Question 17

What is the anatomical position of the SA node?

Answer 17

In the right atrium near the opening of the SVC

Question 18

What is the anatomical position of the AV node?

Answer 18

lies in between the entrance to the tricuspid valve and the coronary sinus

Question 19

what is the only conductive route through the fibrous skeleton?

Answer 19

AV bundle of His

Question 20

What is the function of Purkinje fibres?

Answer 20

They spread the electrical conduction through the ventricles

Question 21

Describe how contraction occurs in the heart.

Answer 21

contraction is initiated by the SA node.
The SA node impulses the rhythm of the heart
conduction then passes down to the apex of the heart so that ventricular contraction is towards the atrioventricular valves

Question 22

What effect does sympathetic innervation have on the heart?

Answer 22

• Increases heart rate

- increases force of contraction

Question 23

what effect does parasympathetic innervation have on the heart?

Answer 23

• decreases heart rate

- decreasing the calibre of the coronary arteries

Question 24

What innervates the heart sympathetically?

Answer 24

Sympathetic cardiac nerves from both sympathetic trunks

Question 25

What is the parasympathetic innervation of the heart?

Answer 25

parasympathetic branches from both Right and left Vagus nerves

Question 26

Where do sympathetic efferents return to from the heart?

Answer 26

their site of origin from spinal cord T1 to T4

Question 27

What is the cardiac plexus formed of?

Answer 27

a mix of parasympathetic and sympathetic nerves

Question 28

where is the cardiac plexus situated?

Answer 28

adjacent to the bifurcation of pulmonary trunk and trachea

Question 29

What is the function of the cardiac plexus?

Answer 29

sends efferent and afferent branches to the SA node, AV node, cardiac musculature and coronary arteries

Question 30

What is an inferior infarct and what does it cause?

Answer 30

• obstruction to the right coronary artery

- likely to cause arrhythmias

Question 31

what is an anterior infract?

Answer 31

obstruction to the left coronary artery, specifically the LAD or anterior inter ventricular branch

Question 32

What are the dangers of an anterior infarct?

Answer 32

Cause catastrophic loss of left ventricular function and the ischaemia may also lead to ventricular fibrillation= cardiac arrest

Question 33

what is a lateral infarct?

Answer 33

obstruction of left circumflex artery